Upgrade to 2.10.x and keep 2.9.x to another branch.
Upgrade to 2.10.x and keep 2.9.x to another branch.

ravihuang/gerrit_cn,garethjevans/docker-gerrit,ravihuang/gerrit_cn,piete/docker-gerrit,ravihuang/zuul,openfrontier/docker-gerrit